Distribution

Distribution of the Highland Guan

eBird range map for Highland Guan

Distribution in the Americas

Highland Guan is resident, and is restricted to the highlands of southern Mexico and northern Central America. The species has been reliably reported in the southern Mexican states of Oaxaca and Chiapas, and in the Central American countries Guatemala, El Salvador, Honduras, and western Nicaragua (Eisermann et al. 2006). A report from the Maya Mountains in Belize (Vannini and Rockstroh 1997, González-García et al. 2001, del Hoyo and Motis 2004) is probably erroneous (Jones and Vallely 2001, Jones 2003, Eisermann et al. 2006). Most records are within the altitudinal range between 900 and 3000 m. Low elevation records at 300-800 m (Hoffmeister 1951, Álvarez del Toro 1980, González-García et al. 2001, Eisermann 2005, Eisermann et al. 2006, Eisermann and Avendaño 2007a) may indicate dispersal or altitudinal migration (del Hoyo and Motis 2004, Eisermann et al. 2006). The area of occurrence, which is a polygon enclosing all records, has a size of about 140,000 km2 (Eisermann et al. 2006). Because of the isolated nature of optimal habitat on mountain tops, the area of occupancy, which is the sum of all patches of occurrence, has a size of only 15,200 km2 (Eisermann et al. 2006).

Distribution outside the Americas

Endemic to southern Mexico and northern Central America.

Habitat

Highland Guan occurs mainly in old-growth cloud forest and pine-oak forest, but it also has been recorded in adjacent low-canopy secondary growth forest, and plantations of pine (Pinus spp.) and cypress (Neocupressus lusitanicus), as well as coffee plantations with a canopy of shade trees (Eisermann et al. 2006; K. Eisermann, personal observations). Renner (2005) found a habitat preference of Highland Guan for old-growth cloud forest compared to adjacent secondary growth forest, but abundance was similar between undisturbed and disturbed primary cloud forest (Eisermann and Schulz 2005).

Historical changes

Populations of Highland Guan have been declining due to habitat alterations and hunting (Brooks and Strahl 2000). Historically, the species was reported from at least 65 sites, and it has been confirmed recently at 53 sites (Eisermann et al. 2006). Deforestation rates in the species’ range was about 12% from 1990-2000 (FAO 2003). Combined with a rapid human population growth, Highland Guan populations presumably declined 30% or more between 1995 and 2005 due to habitat destruction and exploitation (Eisermann et al. 2006).

Fossil history

Several fossil taxa of Galliformes have been classified in earlier studies as members of the family Cracidae (Wetmore 1956, Tordoff and Macdonald 1957, Brodkorb 1964, del Hoyo 1994), with origin in North America. A recent review of morphological characters concluded that these taxa do not belong to the crown group of Galliformes, hence there is no unambiguously identified Palaeogene record of Cracidae (Mayr 2010). Whether the geographic origin of Cracidae is in South America (Vuilleumier 1965) or in North America, with a posterior diversification in South America (del Hoyo 1994), remains therefore unknown because of data deficiency. Molecular analyses suggest that the temporal origin of Cracidae may date in the Late Cretaceous 64-90 million years ago (Pereira et al. 2002).